1. Field of the Invention
The present invention relates to a method and apparatus for imaging visible information on a medium on which an invisible or visible code is formed or to be formed and to an image information management system including such an apparatus.
2. Description of the Related Art
Generally, a digitized document, which is displayed on a display, is accompanied by a problem in not only readability but also portability. Therefore, the digitized document is often printed out to be read or to be carried around for use. On the other hand, such a printed document is often corrected. However, since the original digitized document and corrections are not at all linked, it is required to digitally reedit the original document later on. Hence, it is desired that a system automatically reflecting a correction of a printed document on its original digitized document, that is, a paper-based tablet system, be realized. For such a system, first, it is necessary to obtain the coordinates of the tip part of an input device on a sheet of paper.
Japanese Laid-Open Patent Application No. 9-101864 discloses an apparatus composed of a plurality of information display media, a plurality of information storage media, and an information recording apparatus. The entire part of each information display medium is like a sheet of paper, and each information display medium correctably displays and retains a variety of information. According to this system, information input to the information recording apparatus by handwriting is displayed on the information display media or stored in the information storage media, and information read out from the information storage media by the information recording apparatus is also displayed on the information display media. The information display media not only retains but also freely corrects or deletes the displayed information. Accordingly, a document can be made or stored without consuming paper.
Japanese Laid-Open Patent Application No. 61-296421 discloses an apparatus that includes a coordinate panel on which optically readable code symbols are arranged in a matrix so as to obtain coordinate information by reading the code symbols. Japanese Laid-Open Patent Application No. 7-141104 discloses an apparatus of the same technical contents.
Japanese Laid-Open Patent Application No. 7-244657 discloses an apparatus that edits a document by reading barcodes of file information such as file names printed on sheets of paper when correction is made on the paper sheets.
Further, Japanese Laid-Open Patent Application No. 2000-215000 discloses an information processing system where an invisible code having characteristic position information is preprinted on each information display medium on which reversible recording is performable, and correction information is recognized by the invisible information. The invisible code is used for information security purposes.
Furthermore, according to a coordinate input apparatus, an information processing system, and a medium disclosed in Japanese Laid-Open Patent Application No. 2000-293303, optically readable code symbols are arranged in a matrix on a sheet of paper, and the code symbols are read by a micro-camera provided to a pen as corrections are made on the paper sheet by the pen so that coordinate information can be obtained simultaneously with correction information. Thereby, the correction information, which is read in real time, is correlated to the information of the paper sheet before correction.
As means for retaining a variety of information such as characters and images in a visible state, Japanese Laid-Open Patent Application No. 9-101864 proposes the technique that is a combination of the merits of traditional means of recording information on a paper sheet and means of recording information on a computer including a display and a memory, where the advantages and disadvantages of both means are considered. In other words, Japanese Laid-Open Patent Application No. 9-101864 discloses the apparatus that can rewrite information input by handwriting or created by a computer to be recorded on a recording medium many times (that is, the recording medium is not consumed like paper sheets) so as to be able to process the information as computer-processible digital information that can be stored in memory and output to or input from outside.
However, from a usability point of view, this apparatus, which requires a plurality of information display media having information written thereto or printed thereon to be placed on the tablet so that corrections are made on the media, is inconvenient since the apparatus needs the tablet to be carried around with the information display media when necessary.
Further, for personal use of individuals, as much convenience and functionality as those in the case of writing information on traditional paper sheets by using writing instruments should be achieved. However, users may feel differently in writing work using the tablet from the way they feel in writing information on the paper sheets using the writing instruments, thus having uncomfortable feeling.
These disadvantages are common to the techniques disclosed in Japanese Laid-Open Patent Applications No. 61-296421 and No. 7-141104.
According to the technique disclosed in Japanese Laid-Open Patent Application No. 7-244657, when corrections are made on the tablet, a document is edited by reading the barcode on each paper sheet. However, this requires troublesome work of reading the barcode of each paper sheet in editing the document.
On the other hand, according to the system disclosed in Japanese Laid-Open Patent Application No. 2000-293303, when a printed document is corrected, corrections are automatically reflected on its original digitized document. However, this type of system requires correlating the original digitized document with the recording medium of the printed document, and it is desirable that the correlation be made as automatically as possible with the least human intervention possible.
Further, in the case of Japanese Laid-Open Patent Application No. 2000-215000, an information display medium is limited to the one on which reversible recording is performable, and there is no description of how visible information is printed on the information display medium.
Generally, the invisible code is printed with ink using an ultraviolet (UV) luminescent material, a near infrared luminescent material, or a near infrared absorbing material. The invisible code is recognized as an image by image acquisition means such as a charge-coupled device (CCD) detecting light in the UV spectral region or the near infrared spectral region. However, if corrections are made or an image is formed on a medium printed with such an invisible code with any of materials that absorb light in the above-described spectral regions, it is extremely difficult or impossible to recognize the invisible code. This is the case not only with the invisible code but also with a visible code printed in a visible but visually quiet color, such as a light gray. Some near infrared absorbing pigments are of visible colors such as the light gray.